This invention relates to a clamping ring for connecting cylindrical units of missiles, which have each a circumferential projection having an outer contour and a flat-conical engagement surface. The clamping ring comprises: a circumferential portion bent substantially to an arc of a circle and having an inner and an outer surface, a first and a second front surface, a first and a second end and two rims; clamping means adapted to act on said first and second end of said circumferential portion in order to tighten said ends; a central area having an inner surface and an outer surface; a first and a second cheek extending along said rims and having flat-conical engagement surfaces corresponding to said flat-conical engagement surfaces of said circumferential projections of said cylindrical units to be connected, transitions being defined between said central area and said engagement surfaces of said cheeks; wherein: said clamping ring extends with said cheeks over said circumferential projections of said units; and said engagement surfaces of said clamping ring engage said engagement surfaces of said circumferential projections of said cylindrical units when said clamping ring is tightened.
Target-tracking missiles consist of a plurality of substantially tubular or cylindrical units, for example a seeker head, the electronical unit, the warhead and the driving mechanism. Such units are interconnected by means of clamping rings. The clamping rings are elements, which are bent approximately to an arc of a circle. The ends of the clamping ring are tightened in circumferential direction by means of a turnbuckle. At its inner side the clamping ring has cheeks along its rims. The cheeks extend inwards and the clamping ring extends with these cheeks over circumferential projections of the units to be interconnected. When the clamping ring is tightened, these circumferential projections are pulled together and attached to each other. For this purpose, the two cheeks of the clamping ring have flat-conical engagement surfaces of the inner sides facing each other. These engagement surfaces of the cheeks engage engagement surfaces on the circumferential projections provided at the units. These engagement surfaces of the circumferential projections are flat-conical corresponding to the engagement surfaces of the cheeks.
Usually the circumferential projections of the units engage each other with their front surfaces. The ends of the units can be inserted into each other. The circumferential projections on the units to be interconnected can have cylindrical peripheral surfaces having different radii. A cylindrical peripheral surface can, for example, be connected to the front surface of the circumferential projection by means of a conical surface. The circumferential projections can be provided at sections, which are displaced radially inwards relative to the cylindrical peripheral surface of the unit, such that the clamping ring extending over the projections does not substantially project beyond the peripheral surface of the missile. This is desired for aerodynamical reasons. The cheeks of the clamping ring can project differently far inwards relative to the central area of the clamping ring.
A prior art clamping ring of the type mentioned above is shaped such that, taking all tolerances of the units into consideration, the maximum outer diameter of a circumferential projection of a unit is substantially larger than the corresponding inner diameter of the clamping ring. Thus, when the clamping ring is tightened by means of a turnbuckle, the inner surface of the central area of the clamping ring does not at any place positively engage the outer surface of a circumferential projection formed on the units.
In practice it has been found, that the prior art clamping rings can break under loads occuring in practice. This can lead to serious consequences. It is not possible just to reinforce the clamping rings because of constuctive requirements, for example the shape of the circumferential projections of the units to be interconnected and the radially allowed maximum dimensions of the clamping rings.
The object of the present invention is to increase the strength of the clamping ring, taking the available space for the clamping ring into consideration, particularly the radial dimensions of the clamping ring.
According to the invention this is achieved in that the inner surface of the central area of the clamping ring is free from edges and guided tightly about the outer contours of the circumferential projections of the units, and rounded circumferential recesses are provided at the transitions between the inner surface of the central area and the engagement surfaces of the cheeks of the clamping ring in order to achieve large transition radii.
Preferably the outer surface of the clamping ring has a substantially cylindrical section in the central area and substantially conical sections in the area of the cheeks, the transition between the cylindrical section and the conical sections being rounded.
The invention is particularly based on the discovery, that overload of the clamping ring can occur in the edges on the inside between the central area of the clamping ring and the cheeks. There, the radius of curvature is small and, thus, the stresses in the material are high there. According to the present invention the inner surface of the central area is, in fact, guided as tightly as possible around the outer contours of the circumferential projections of the units, but the inner surface is smooth and continuous without edges. Thus, at one hand, the thickness of the clamping ring is made as large as possible, and, on the other hand, steps and edges are avoided, at which small radii of curvature and high material stresses can occur. Furthermore, rounded circumferential recesses are provided between the central area and the cheeks. This leads to removal of material, but the radius of curvature is increased. This reduces the specific material stresses.
In order to increase the thickness of the clamping ring without exceeding the allowed radial dimensions, in a preferred embodiment of the clamping ring the outer surface of the clamping ring has a substantially cylindrical section in the central area. From this section the outer surface continues in a rounded manner in a substantially conical section, which extends inwards to the radial front surface of the clamping ring. Thus, the outer contour of the clamping ring extends outside the outer contour of prior art clamping rings. This results in increase of the strength, without exceeding the allowed radial maximum dimensions of the clamping ring.
It has been shown, that the combination of the features of the invention leads to a considerable increase of the strength of the clamping ring. The dimensions of the clamping ring according to the present invention are such, that this clamping ring can be used instead of prior art clamping rings. Missiles can be retrofitted with the clamping rings according to the present invention without change in their design.
Further objects and features of the invention will be apparent to a person skilled in the art from the following specification of a preferred embodiment when read in conjunction with the appended claims.